1. Field of the Invention
The present invention relates to a novel 8-hydroxyquinoline acetamide compound, an 8-hydroxyquinoline thioamide and use thereof. More specifically, the present invention relates to a novel 8-hydroxyquinoline thioamide compound suitable for use as a selective chemodosimeter that shows considerable high detection sensitivity to mercury ions, an 8-hydroxyquinoline acetamide compound as an intermediate thereof, preparation thereof, and mercury ion-selective detection using the same.
2. Description of the Related Art
As used herein, the term “chemodosimeter” refers to a detection system that detects metal cations as a detection target via a chemical reaction, i.e. stoichiometric reaction. There are some differences between the chemodosimeter and the chemical sensor. Firstly, the chemodosimeter must react stoichiometrically with the target metal, whereas the chemical sensor interacts with the target in a very selective or specific way. Secondly, expression of specific fluorescent properties is irreversible which results from the structural changes of the chemodosimeter through the chemical reaction. In other words, once the chemical change undergone, the chemodosimeter does not return to an initial state in the same reaction system. In contrast, as the chemical sensor emits fluorescence via binding with the metal cations (without chemical changes), the thus-bound cations can be eliminated with the use of a strong chelating agent such as EDTA. Therefore, the chemical sensor involves a reversible process.
Recently, a great deal of research has been conducted to develop chemodosimeters and chemical sensors for use in selective and efficient detection of chemically or biochemically important ionic materials. It has been known that the most desirable technique to develop sensors selective and sensitive for a specific material is the use of a well-known and efficient binding site coupled with a suitable signaling subunit. In particular, various fluorescent functional groups have been introduced as the signaling subunit. This is because fluorescent functional groups have high sensitivity and easy signal-convertibility.
Various selective fluorescent chemodosimeters have been reported to date. For example, fluorescent-sensitive properties selective for mercury ions involved in desulfurization was reported by (a) Chae, M.-Y.; Czarnik, A. W. J. Am. Chem. Soc. 1992, 114, 9704. (b) Yang, Y. K.; Yook, K. J.; Tae, J. J. Am. Chem. Soc. 2005, 127, 16760. (c) Zhang, G.; Zhang, D.; Yin, S.; Yang, X.; Shuai, Z.; Zhu, D. Chem. Commun. 2005, 2161. In particular, Chae et. al., suggested a 9-[(methyl-amino)thiocarbonyl]anthracene compound serving as a chemodosimeter that expresses changes in the fluorescence emission behavior which results from desulfurization by mercury and silver ions. However, there remain problems in that the compound is selective for both mercury ions and silver ions and incomplete desulfurization (e.g. 87%) is carried out after 10 min.
Furthermore, a selective fluorescent variation for copper ions (Cu2+) was reported by Dujols, V.; Ford, F.; Czarnik, A. W. J. Am. Chem. Soc. 1997, 119, 7386. Optically electrochemically sensitive properties for heavy metals such as mercury (Hg2+), lead (Pb2+) and cadmium (Cd2+) were reported by (a) Takahashi, Y.; Kasai, H.; Nakanishi, H.; Suzuki, T. M. Angew. Chem., Int. Ed. 2006, 45, 913, (b) Oehme, I.; Wolfbeis, O, S. Mikrochim. Acta 1997, 126, 177, (c) Bonfil, Y.; Brand, M.; Kirowa-Eisner, E. Anal. Chim. Acta 2002, 464, 99, etc. A selective fluorescent sensitive properties for alkali metal ions and alkaline earth metal ions was reported by (a) Kollmannsberger, M.; Rurack, K.; Resch-Genger, U; Rettig, W; Daub, J. Chem. Phys. Lett. 2000, 329, 363, (b) Rurack, K; Sczepan, M.; Spieles, M.; Resch-Genger, U.; Rettig, W. Chem. Phys. Lett. 2000, 320, 87, etc.
Meanwhile, toxicity of mercury ions was well-known in environmental fields, and continuous development for various sensors capable of sensitively and selectively detecting mercury ions under various conditions have been thus made in the fields. The sensors necessarily exhibit significant variation in spectroscopic properties in response to binding to mercury ions. The use of fluorescent properties for the sensors is based on ease of quantitative analysis or signal conversion.
However, the fore-mentioned methods for detecting metal ions, in particular, chemodosimeters exhibiting a selective fluorescent sensitivity for mercury ions involved in desulfurization have some problems in that it takes a long time to increase fluorescence intensity in response to desulfurization or has low detection sensitivity because of an insufficient increase in the level of fluorescence intensity, when compared to the value prior to desulfurization. Furthermore, there is a limitation on exclusive detection of mercury ions because of undesired detection of other ions (e.g. silver ions) in addition to mercury ions.